The purpose of this task is to improve developer productivity by reducing Scala build cycle time in Eclipse.

The idea is to take the chunks of code we're no longer planning to use going forward, and put them into a separate sub-project which can still be open, and available for us to surf and learn from and decipher, but which aren't part of the primary edit-compile-test cycle.

This is kind of like daffodil-lib, except this is for code we think is going away, but we still want to learn from, as in we're rewriting the feature, but we still want to try to figure out what the prior-generation code was doing, so we want it there and live, and even runnable so we can walk it in the debugger. But as we're not changing the prior-gen code anymore, it shouldn't need to be compiled (at least not very much.)

We have this src-unused directory, but that specifically isn't great for this because according to eclipse, it's not a "source" directory, and so isn't compiled at all. What we want is a separate project where the prior-gen code sits, is compiled, can be rapidly navigated like any source code, where you can jump from definition to definition using IDE features, and so forth.

Suggest sub-projects/legacy/src/... as the name for this project.

This would be on the newBackEnd branch.